Effect of Σ3 grain boundaries on microstructure and properties of oriented Fe-6.5 wt%Si in twin-roll strip casting

Oriented Fe-6.5 wt%Si alloy with excellent magnetic properties was prepared by twin-roll strip casting (TRSC). We studied the abnormal Sigma 3 grain boundaries in the as-cast strip. The experimental results demonstrated that the Sigma 3 grain boundary (GB) in oriented Fe-6.5 wt%Si steel had a good thermal stability, which could refine the microstructure by inhibiting growth of structure in as-cast strip. Moreover, the Sigma 3 GB in Fe-6.5 wt%Si as-cast strip could improve the toughness of matrix and restrain the propagation of cracks, which was beneficial to its plastic working. The Sigma 3 GB was relatively stable during warm rolling and could be inherited partly after annealing. At the same time, the low migration rate of Sigma 3 GB in primary recrystallization structure could stabilize the matrix and help to obtain the abnormal growth of Goss grains. The finished Fe-6.5 wt%Si steel had excellent magnetic properties, B-800 and P-10/50 were 1.76 T and 0.59 W/kg, respectively.

Automated summary

An oriented Fe-6.5 wt%Si alloy with excellent magnetic properties was successfully prepared using twin-roll strip casting. The abnormal Sigma 3 grain boundaries in the as-cast strip were studied. The experimental results showed that the Sigma 3 grain boundary in the alloy had good thermal stability and could refine the microstructure by inhibiting growth of structure in the as-cast strip. It also improved the toughness of the matrix and restrained crack propagation, which was beneficial for plastic working. Moreover, the low migration rate of the Sigma 3 grain boundary stabilized the matrix and helped achieve abnormal growth of Goss grains.